Calculating sum based on quarters

I am trying to get the sum of totals based on quarter system. [10,20,30,40,50,60,70,80,90] - Initial array

The result I am looking for is [60, 150, 70, 80, 90] Where Q1 = 10+20+30 = 60 Q2 = 40+50+60 = 150 Q3 will be complete only if pass in October value.

I am confused with the logic I have

var adata = [10,20,30,40,50,60,70,80,90];
process(adata, "Sept 2014");

function process(adata, date){
    var today = new Date(date) || new Date();
    var aQuarter = [];
        var tempQuarter = [];
    var aSum = [];
    //var quarter = Math.floor((today.getMonth() + 3)/3);
    for(var i = 0; i<= today.getMonth(); i++) {
        aQuarter.push(adata[i]);
    }
    tempQuarter = adata.slice();
    if(tempQuarter.length > 3) {
                var i = 0;
        var sum = [];
                while(i <= 2) {
                        sum[i] = aQuarter.shift();
                        i++;
                }
        console.log(sum);
                aQuarter.unshift(sum);
        }
    if(tempQuarter.length > 6){
                var i = 0;
        var sum = [];
                while(i+1 <= 3) {
                        sum[i] = aQuarter.shift();
                        i++;
                }
                aQuarter.unshift(sum);
        }
    console.log(aQuarter);
    if(tempQuarter.length > 9){
                var i = 0;
                while(i+2 <= 4) {
                        sum[i] = aQuarter.shift();
                        i++;
                }
        }
}

jsfiddle